Lanzhou is a prefecture-level city and capital of Gansu province in northwestern China.Lanzhou is situated on the upper course of the Yellow River, where the river emerges from the mountains. It has been a center since early times, being at the southern end of the route leading via the Hexi Corridor across Central Asia. It also commands the approaches to the ancient capital area of Chang´an (modern Xi´an) in Shaanxi province from both the west and the northwest, as well as from the area of Qinghai Lake via the upper waters of the Yellow River and its tributaries.